Montserrat Volcano Observatory

Daily Report
Report for the period 16:00 27 April
to 16:00 28 April 1997
The current alert level is AMBER

The volcano has been relatively quiet during the last 24 hours, with rockfalls and occasional small pyroclastic flows into the White River valley. Low cloud has restricted views of the top of the dome.

The broadband seismic network recorded a total of 81 rockfall signals during the past 24 hours, which is an increase from yesterday. There were 22 long-period earthquakes, with 14 of these triggering rockfalls from the dome. There were no hybrid earthquakes and only one volcano-tectonic earthquake recorded today. This style of seismicity has dominated events over the past 2 weeks and is associated with continued moderate rates of dome growth.

Visibility was poor today, and no views of the dome were possible. The remaining crack on Chance's Peak was measured this morning, and rockfalls could be heard in the Galway's Wall area at that time. Ash production during the day has been low, although it has been masked by the low cloud.

Measurements of Crack 2 on Chance's Peak showed that opening of this crack has slowed significantly; the opening was about 6 mm and sideways movement about 7 mm since the last measurements 3 weeks ago. This suggests a reduction in the stress on Galway's Wall and Chance's Peak, which are under constant pressure from the growing dome in the crater.

A long-occupation (20 hour) GPS survey was started today to measure the line length between Chance's Peak and Harris Lookout - the survey will finish and be processed tomorrow. The results should give further indication of any movements of the Chance's Peak area.

The volcano remains dangerous, and only essential visits should be made to the evacuated zone. There is still a lot of ash blowing around, despite the rain of last night, so people should wear masks when in the affected areas. The Tar River and White River valleys are extremely dangerous, and should not be entered under any circumstances.

Montserrat Volcano Observatory